Various test methods for evaluating the strength of hand chain hoists

Various test methods for evaluating the strength of hand Chain Hoists
In the industrial field, hand chain hoists are widely used in many industries such as construction, manufacturing, and ship repair as a common light and small lifting equipment. Its strength is directly related to the safety and efficiency of the operation, so it is crucial to accurately evaluate the strength. This article will explore in depth the various test methods that can be used to evaluate the strength of hand chain hoists.

1. Static load test
Static load test is one of the important methods for evaluating the strength of hand chain hoists. It mainly tests its load-bearing capacity in a static state by gradually applying a static load to the hand chain hoist. The specific operation is to install the hand chain hoist on a special test bench and gradually load it to 1.5 times the rated load for 10 minutes. During this process, observe whether the various components of the hand chain hoist, such as the hook, chain, shell, etc., have permanent deformation or breakage. If there is no permanent deformation of the components that affects the performance, it means that the strength of the hand chain hoist under static load conditions is qualified. This test method can effectively evaluate the overall strength and stability of the hand chain hoist when it is subjected to static load.

2. Dynamic load test
The dynamic load test is used to simulate the stress of the hand chain hoist under actual working conditions to evaluate its strength and reliability under dynamic conditions. During the test, the hand chain hoist is loaded with 1.1 times the rated load on a special test bench to perform the operation of rising and falling once, and the wire rope moves no less than 200mm each time. By observing the operation of the hand chain hoist under dynamic load, including whether there is jamming and whether the operation is smooth, it is judged whether its strength meets the dynamic working requirements. The dynamic load test can reveal the force response and interaction of each component of the hand chain hoist during the movement process, ensuring its safety and reliability in actual use.

3. Hook test
The hook is a key component of the hand chain hoist, which directly bears the weight of the hoisted object, so the evaluation of its strength is particularly important. The hook test usually includes two situations:
Gradually loading to 2 times the rated load: Install the hook on the material testing machine, gradually apply 2 times the rated load through the center of the hook cavity, keep it for 1 minute, then remove the load and check the deformation of the hook mouth. The deformation shall not exceed 0.25%. This can effectively evaluate the elastic deformation capacity of the hook under overload conditions and ensure that it can still return to normal working state after a certain degree of overload.
Gradually loading to 4 times the rated load: Also install the hook on the material testing machine and gradually apply 4 times the rated load. The hook should be able to support reliably for 1 minute. This test method is mainly used to verify the ultimate load-bearing capacity of the hook to ensure that the hook will not break or other serious failures in extreme cases, thereby ensuring the safety of the operation.

4. Chain test
As another important component of the hand chain hoist, the strength of the chain is directly related to the performance and safety of the entire equipment. The chain test mainly includes the following aspects:
Chain tensile strength test: Use a universal material testing machine to perform a tensile test on the chain, gradually apply tension until the chain breaks, and measure the maximum tension when it breaks to evaluate whether the tensile strength of the chain meets the standard requirements. This can ensure that the chain will not break when it is subjected to a large load.
Chain wear test: By measuring the degree of wear of the chain, such as the reduction in chain diameter and the deformation of the chain link, it is determined whether the chain has decreased in strength due to long-term use. Generally, measuring tools such as vernier calipers can be used to accurately measure various parts of the chain and compare them with standard dimensions to determine whether the chain needs to be replaced.
Chain flexibility test: Check the activity and flexibility of the chain to ensure that the chain will not get stuck during use. The flexibility of the chain can be tested by manually pulling the chain or using special equipment, which is of great significance to ensure the smooth operation and work efficiency of the hand chain hoist.

5. Material analysis
Understanding the performance of the materials used to make the hand chain hoist plays a fundamental role in evaluating its strength. Material analysis techniques such as spectroscopy are usually used to determine the composition and properties of the materials used to manufacture hand chain hoists, such as the content of elements such as carbon, sulfur, phosphorus, silicon, manganese, titanium, chromium, and molybdenum. By comparing with standard material performance indicators, it is possible to determine whether the material meets the quality requirements, thereby essentially evaluating the strength potential of the hand chain hoist. For example, if the impurity content in the material is too high or the content of key alloy elements is insufficient, the strength of the hand chain hoist may decrease, affecting its service life and safety.

6. Nondestructive testing
Nondestructive testing is a method of detecting internal and surface defects of the hand chain hoist without destroying its structure and performance. Commonly used technologies include:
Ultrasonic testing: Using the principle that ultrasonic waves will reflect when encountering defects when propagating inside the metal, detect whether there are cracks, pores, inclusions and other defects inside the metal parts of the hand chain hoist, such as chains, hooks, shells, etc. By analyzing the characteristics of ultrasonic signals, the location, size and shape of defects can be accurately determined, providing an important basis for evaluating the strength of hand chain hoists. For example, if a large crack or pore is found inside the chain, it may become a stress concentration point, reducing the strength of the chain and increasing the risk of breakage.
Magnetic particle testing: Mainly used to detect surface and near-surface defects of magnetic materials. The magnetic parts of the hand chain hoist are magnetized and then sprinkled with magnetic powder. If there is a defect, the magnetic powder will gather at the defect to form a display, so that the location and shape of the defect can be intuitively found. This method is very effective for detecting tiny cracks, wear and other defects on the surface of the hand chain hoist. It can timely discover potential strength weaknesses and take corresponding measures to repair or replace them.